This invention relates in general to power supply systems for PC (Personal Computer) based telephony systems, and more specifically to a power supply housed in a 5.25 inch standard disk-drive housing within a PC server cabinet for receiving external loop feed voltage (xe2x88x9248 VDC) from an external source and generating ringing voltage (75 VAC) therefrom.
Significant potential problems exist in the integration of telecommunications into OEM PC cabinets. The root cause for these problems is that the power requirements for telephony systems are different from those of off-the-shelf PCs. For example, telephony (viz. POTS) line support requires the provision of a ringing power supply (75 VAC/xe2x88x9248 VDC), which is a hazardous voltage. PC cabinets are normally user-accessible, which invites accidental exposure of untrained personnel to these dangerous voltage levels. Also, PC server cabinets do not provide dedicated telephony signal grounding.
One solution to the problem of PC server connectivity to telecommunications equipment is the provision of a peripheral cabinet incorporating a Telecommunications Hub which attaches to a PC, as set forth in U.S. patent application Ser. No. 08/733,807, the contents of which are incorporated herein. This solution can be cost-prohibitive when implemented in a small configuration. Other solutions use external power supplies for generating both loop feed and ringing voltages, which also give rise to potential hazards. The ringing voltage is above the level generally regarded as a secondary hazardous voltage by international safety approvals bodies (30 VAC). Accordingly, this solution gives rise to potentially hazardous voltages within the enclosure, notwithstanding that the enclosure is intended to be accessed only by trained personnel for service.
According to the present invention, a system is provided for supplying loop feed voltage (xe2x88x9248 VDC) from an external source such as a stand-alone power supply or CO (Central Office) battery and generating the ringing voltage (75 VAC) from the loop feed voltage. For universal applicability, the ringing voltage generator is preferably located in a 5.25 inch standard disk-drive housing, allowing it to fit into any PC. Limiting the output of this module to Telecommunication Network Voltage levels means that the PC can be safely serviced with the 48V power left on (although this is not recommended).